Medical instability in typical and atypical adolescent anorexia nervosa: a systematic review and meta-analysis

Two identical twin pairs discordant for longstanding anorexia nervosa and OSFED: lived experience accounts of eating disorder and recovery processes

Research into the risk of anorexia nervosa (AN) has examined twin pairs to further the understanding of the contributions of genetics, trait inheritance, and environmental factors to eating disorder (ED) development. Investigations of twin experiences of EDs have been biologically-based and have not considered the qualitative, phenomenological aspects of twin experiences. A gap in the literature exists regarding understanding of discordant twins with EDs. This research was developed in response, with the aim to deepen understanding of AN in discordant twins and to create novel ideas for further research and testing. The case studies presented in this article provide lived experience insights of two identical discordant twin pairs: one twin pair discordant for longstanding AN and one twin pair discordant for 'atypical' AN (the twin with AN has recovered). The perspectives and experiences of each co-twin (one with AN and one without) explore a number of factors that may have contributed to twin discordance in these cases, and how each twin has responded to the impact of AN in their lives. Through use of first-person accounts in case study presentation, this article centres social justice values of lived experience leadership and involvement in research. This article aims to extend current knowledge and understanding of EDs in discordant twins, particularly regarding risk for ED development, ED duration, diagnosis and treatment, and recovery processes.

Impact of electrolyte abnormalities and adverse outcomes in persons with eating disorders: A systematic review protocol

BACKGROUND

Electrolytes (sodium, potassium, calcium, magnesium, chloride, phosphate) are required in specific amounts for proper functioning of the human body. Although the body has different organ systems, such as the kidneys, that regulate electrolyte levels in the blood, electrolyte abnormalities occur frequently in people with eating disorders. The objective of this review will be to examine the association between electrolyte imbalances and adverse outcomes in people with eating disorders.

METHODS

A systematic review of studies on eating and electrolyte disorders shall be conducted. Electronic searches shall be done in the Ovid MEDLINE, EMBASE, and PsycINFO databases. Selected studies shall include randomized control trials (RCTs), non-randomized controlled trials, and cross-sectional studies published in English or French. Quality appraisal of studies and a narrative synthesis of extracted data shall be conducted.

DISCUSSION

This review will synthesize existing evidence on electrolyte abnormalities in people with eating disorders. It will identify the type of electrolyte imbalances, their impact, and outcomes in people with eating disorders. We anticipate that information that will be useful to policy makers and clinicians in designing better policies to prevent eating disorders and or manage people with eating disorders shall be elucidated in this study.

DISSEMINATION

The final manuscript will be submitted for publication in a journal.

REVIEW REGISTRATION

This protocol has been registered with the International Prospective Register of Systematic Reviews (PROSPERO); registration number CRD42023477497.

A prospective observational study comparing rates of medical instability between adolescents with typical and atypical anorexia nervosa

BACKGROUND

Recognition of atypical anorexia nervosa (AAN) has challenged underweight as a defining factor of illness severity in anorexia nervosa (AN). The present study aimed to compare rates of medical instability in adolescents with underweight (AN) and non-underweight (AAN) anorexia nervosa.

METHODS

The study examined assessment data from specialist eating disorder services in the UK between January and December 2022. Participants (n = 205) aged 11-18 years were recruited across eight eating disorder clinics and diagnosed with AN (n = 113) or AAN (n = 92) after clinical assessment. Parameters associated with risk of medical instability were compared between AN and AAN groups, using t tests and regression analysis.

RESULTS

Rates of bradycardia and hypotension did not differ significantly between AN and AAN groups (p = 0.239 and p = 0.289). Although white blood cell counts were lower in the AN group, rates of leukopaenia could not be statistically compared as a result of there being too few counts in at least one group. No incidences of hypophosphataemia were found in the sample. A significant regression equation was found for percentage median body mass index, but not rate of weight loss, as a predictor of blood pressure, serum phosphorous and magnesium.

CONCLUSIONS

Our findings indicate that medical instability occurs across a range of body weights in young people with AN and AAN. Although certain parameters of risk such as blood pressure, serum phosphorous and magnesium may be worsened at lower weight, both AN and AAN are serious mental health conditions that can lead to medical instability.

Comparing changes in eating disorder psychopathology and comorbid symptoms over treatment in anorexia nervosa and atypical anorexia nervosa in a partial hospitalization program

OBJECTIVE

The objective of this study is to compare treatment trajectories in anorexia nervosa (AN) and atypical AN.

METHOD

Adolescents and adults with AN (n = 319) or atypical AN (n = 67) in a partial hospitalization program (PHP) completed diagnostic interviews and self-report questionnaires measuring eating disorder (ED), depression, and anxiety symptoms throughout treatment.

RESULTS

Premorbid weight loss did not differ between diagnoses. Individuals with atypical AN had more comorbid diagnoses, but groups did not differ on specific diagnoses. ED psychopathology and comorbid symptoms of depression/anxiety did not differ at admission between groups nor did rate of change in ED psychopathology and comorbid symptoms of depression/anxiety from admission to 1-month. From admission to discharge, individuals with atypical AN had a faster reduction in ED psychopathology and comorbid symptoms of depression and anxiety (ps < 0.05; rs = 0.01-0.32); however, there were no group differences in ED psychopathology or depression symptoms at discharge (ps>.50; ds = .01-.30). Individuals with atypical AN had lower anxiety at discharge compared to individuals with AN (p = 0.05; d = .4). Length of stay did not differ between groups (p = 0.11; d = .21).

DISCUSSION

Groups had similar ED treatment trajectories, suggesting more similarities than differences. PHP may also be effective for AAN.

PUBLIC SIGNIFICANCE

This study supports previous research that individuals with AN and atypical AN have more similarities than differences. Results from this study indicate that individuals with AN and atypical AN have similar treatment outcomes for both ED psychopathology and depressive symptoms; however, individuals with atypical AN have lower anxiety symptoms at discharge compared to individuals with AN. AN and atypical AN also have more symptom similarity at admission and throughout treatment, which challenges their current designation as distinct disorders.

There is nothing as inconsistent as the OSFED diagnostic criteria

Atypical anorexia nervosa (AAN), purging disorder (PD), night eating syndrome (NES), and subthreshold bulimia nervosa and binge-eating disorder (Sub-BN/BED) are the five categories that comprise the 'Other Specified Feeding or Eating Disorder' (OSFED) category in the Diagnostic and Statistical Manual for Mental Disorders (DSM-5). In this review, we examine problems with the diagnostic criteria that are currently proposed for the five OSFED types. We conclude that the existing diagnostic criteria for OSFED are deficient and fall short of accurately describing the complexity and individuality of those with these eating disorders (EDs). Therefore, to enhance the quality of life of people with OSFED, diagnostic criteria for the condition should be applied uniformly in clinical and research settings.

Affective processes underlying restrictive eating in atypical anorexia nervosa: Comparisons to anorexia nervosa and bulimia nervosa using ecological momentary assessment

OBJECTIVE

Certain symptom and risk/maintenance factor similarities between individuals with atypical anorexia nervosa (AN) and 'typical' AN have been documented, but few studies have investigated how atypical AN compares to bulimia nervosa (BN). Further, the role of affective mechanisms in maintaining restrictive eating in atypical AN has not been examined. The current study investigated whether atypical AN resembles AN and/or BN on affect-related processes using questionnaires and ecological momentary assessment (EMA).

METHOD

Women with atypical AN (n = 24), AN-restrictive subtype, (n = 27), AN-binge eating/purging subtype (n = 34), and BN (n = 58) completed questionnaires measuring depressive symptoms and emotion regulation difficulties. They also completed a 14-day EMA protocol during which they reported negative and positive affect and skipped meals five times/day (signal-contingent surveys) and restrictive eating after meals/snacks (event-contingent surveys).

RESULTS

Diagnostic groups generally did not differ on questionnaire measures nor affective patterns surrounding restrictive eating behaviors. Momentary changes in affect did not predict or follow restriction at meals/snacks, though higher momentary negative affect ratings predicted skipped meals, and higher positive affect was reported after skipped meals. Greater average negative affect and lower average positive affect predicted both restrictive eating behaviors.

DISCUSSION

Across diagnoses, reductions in food intake do not appear to be influenced by momentary changes in affect, though skipping meals may serve an emotion regulation function. Atypical AN seems to resemble AN and BN on affective processes underlying restrictive eating, raising further questions regarding the unique diagnosis of atypical AN.

PUBLIC SIGNIFICANCE

Though atypical anorexia appears to strongly resemble anorexia nervosa, it is less clear how this disorder relates to bulimia nervosa. It is further unknown whether affective-related processes underlie restrictive eating in atypical anorexia nervosa, and how these processes compare to those in anorexia nervosa and bulimia nervosa. Results suggest that atypical anorexia does not differ from anorexia nervosa or bulimia nervosa on emotion-related measures, nor in affective patterns surrounding restrictive eating behaviors.

Differentiating anorexia nervosa and atypical anorexia nervosa with absolute weight cut-offs results in a skewed distribution for premorbid weight among youth

OBJECTIVE

Anorexia nervosa (AN) and atypical AN are conceptualized as distinct illnesses, despite similar characteristics and sequelae. Whereas DSM-5 differentiates youth with AN and atypical AN by the presence of clinical 'underweight' (i.e., 5th BMI percentile for age-and-sex (BMI%)), we hypothesized that using this weight cut-off to discern diagnoses creates a skewed distribution for premorbid weight.

METHOD

Participants included hospitalized youth with AN (n = 165, 43.1%) and atypical AN (n = 218, 56.9%). Frequency analyses and chi-square tests assessed the distribution of premorbid BMI z-scores (BMIz) for diagnosis. Non-parametric Spearman correlations and Stepwise Linear regressions examined relationships between premorbid BMIz, admission BMIz, and weight loss in kg.

RESULTS

Premorbid BMIz distributions differed significantly for diagnosis (p < .001), with an underrepresentation of 'overweight/obesity' (i.e., BMI% ≥ 85th) in AN. Despite commensurate weight loss in AN and atypical AN, patients with premorbid 'overweight/obesity' were 8.31 times more likely to have atypical AN than patients with premorbid BMI% < 85th. Premorbid BMIz explained 57% and 39% of the variance in admission BMIz and weight loss, respectively.

DISCUSSION

Findings support a homogenous model of AN and atypical AN, with weight loss predicted by premorbid BMI in both illnesses. Accordingly, premorbid BMI and weight loss (versus presenting BMI) may better denote the presence of an AN-like phenotype across the weight spectrum. Findings also suggest that differentiating diagnoses with BMI% < 5th requires that youth with higher BMIs lose disproportionately more weight for an AN diagnosis. This is problematic given unique treatment barriers experienced in atypical AN.

PUBLIC SIGNIFICANCE

Anorexia nervosa (AN) and atypical AN are considered distinct conditions in youth, with differential diagnosis hinging upon a presenting weight status of 'underweight' (i.e., BMI percentile for age-and-sex (BMI%) < 5th). In our study, youth with premorbid 'overweight/obesity' (BMI% ≥ 85th) disproportionately remained above this threshold, despite similar weight loss. Coupled with prior evidence for commensurate characteristics and sequelae in both diagnoses, we propose that DSM-5 differentiation of AN and atypical AN inadvertently reinforces weight stigma and may contribute to treatment disparities in atypical AN.

Greater rate of weight loss predicts paediatric hospital admission in adolescent typical and atypical anorexia nervosa

Hospital admissions for eating disorders (ED) are rapidly increasing. Limited research exists evidencing the factors that lead to hospital admissions or their outcomes. The current study aimed to identify predictors of hospital admission in adolescents with anorexia nervosa (AN) or atypical anorexia nervosa (AAN). Prospective observational study including participants (n = 205) aged 11-18 and diagnosed with AN or AAN at initial ED assessment, across eight London clinics. Physical health parameters at assessment, including heart rate, blood pressure, temperature and rate of weight loss, were compared between adolescents who were admitted to a paediatric ward following assessment and those who were not admitted. The mean rate of weight loss prior to assessment was significantly higher, and mean energy intake significantly lower, in the admitted vs not admitted groups (1.2 vs 0.6kg/week, p < 0.001 and 565 kcal/day vs 857 kcal/day, p < 0.001), independent of degree of underweight. No significant differences were identified between groups in all other parameters of physical risk. Underweight adolescents with AN were equally likely to be admitted as non-underweight adolescents with AAN.  Conclusion: This study provides evidence on predictors of hospital admission, from a sample representing the London area. The assessment of weight loss speed, duration and magnitude are recommended as priority parameters that inform the risk of deterioration and the likelihood of hospital admission in adolescent AN and AAN. Further research investigating outcomes of these hospital admission is needed. What is Known: • Hospital admissions for eating disorders (ED) are rapidly increasing. • Limited research exists evidencing the factors that lead to hospital admissions, or their outcomes. What is New: • This study provides evidence on predictors of hospital admission in young people with typical and atypical anorexia nervosa. • Weight loss speed, duration, and magnitude are recommended as priority parameters that inform the risk of deterioration and the likelihood of hospital admission in this patient group.

Comparisons between atypical anorexia nervosa and anorexia nervosa: Psychological and comorbidity patterns

OBJECTIVE

Literature comparing "atypical" anorexia nervosa (atypical AN) and anorexia nervosa (AN) suggests these diagnoses share significant similarities in eating disorder (ED) pathology and psychiatric comorbidities. This study evaluated potential differences in ED pathology, psychiatric comorbidity, associated mechanisms (i.e., ED fears and perfectionism), and demographic factors (i.e., ethnicity and age) between individuals with atypical AN and AN.

METHOD

Data from seven protocols were combined for a total 464 individuals diagnosed with atypical AN (n = 215) or AN (n = 249). Between-group differences in ED severity and behaviors, psychiatric comorbidities, ED fears, perfectionism, and demographic factors were assessed using t-tests, Wilcoxon rank-sum tests, and Fisher's exact test.

RESULTS

Participants with atypical AN reported higher levels of overvaluation of weight and shape than those with AN. Participants with AN scored higher on food-related fears (anxiety about eating, food avoidance behaviors, and feared concerns) and fears of social eating, as well as obsessive-compulsive symptoms. Participants with AN were more likely to identify as Asian or Pacific Islander. No other statistically significant differences were found between groups for overall ED severity, ED behaviors, psychiatric comorbidities, general ED fears, perfectionism, or demographic factors.

DISCUSSION

Overall, results support previous literature indicating limited differences between individuals with atypical AN and AN, though individuals with atypical AN reported more overvaluation of weight and shape and those with AN reported higher food and social eating fears and obsessive-compulsive symptoms. Relatively few overall differences between atypical AN and AN highlight the importance of exploring dimensional conceptualizations of AN as an alternative to the current categorical conceptualization.

PUBLIC SIGNIFICANCE

This study assessed differences among individuals with atypical anorexia nervosa and anorexia nervosa in eating disorder severity and behaviors, comorbid psychiatric diagnoses, associated mechanisms, and demographic factors. Few differences emerged, though participants with atypical anorexia nervosa reported more overvaluation of weight and shape, while those with anorexia nervosa reported more food and social eating fears and higher obsessive-compulsive symptoms. Results support exploration of these diagnoses as a spectrum disorder.

Premorbid body weight predicts weight loss in both anorexia nervosa and atypical anorexia nervosa: Further support for a single underlying disorder

OBJECTIVE

For adolescents, DSM-5 differentiates anorexia nervosa (AN) and atypical AN with the 5th BMI-centile-for-age. We hypothesized that the diagnostic weight cut-off yields (i) lower weight loss in atypical AN and (ii) discrepant premorbid BMI distributions between the two disorders. Prior studies demonstrate that premorbid BMI predicts admission BMI and weight loss in patients with AN. We explore these relationships in atypical AN.

METHOD

Based on admission BMI-centile < or ≥5th, participants included 411 female adolescent inpatients with AN and 49 with atypical AN from our registry study. Regression analysis and t-tests statistically addressed our hypotheses and exploratory correlation analyses compared interrelationships between weight loss, admission BMI, and premorbid BMI in both disorders.

RESULTS

Weight loss in atypical AN was 5.6 kg lower than in AN upon adjustment for admission age, admission height, premorbid weight and duration of illness. Premorbid BMI-standard deviation scores differed by almost one between both disorders. Premorbid BMI and weight loss were strongly correlated in both AN and atypical AN.

DISCUSSION

Whereas the weight cut-off induces discrepancies in premorbid weight and adjusted weight loss, AN and atypical AN overall share strong weight-specific interrelationships that merit etiological consideration. Epidemiological and genetic associations between AN and low body weight may reflect a skewed premorbid BMI distribution. In combination with prior findings for similar psychological and medical characteristics in AN and atypical AN, our findings support a homogenous illness conceptualization. We propose that diagnostic subcategorization based on premorbid BMI, rather than admission BMI, may improve clinical validity.

PUBLIC SIGNIFICANCE

Because body weights of patients with AN must drop below the 5th BMI-centile per DSM-5, they will inherently require greater weight loss than their counterparts with atypical AN of the same sex, age, height and premorbid weight. Indeed, patients with atypical AN had a 5.6 kg lower weight loss after controlling for these variables. In comparison to the reference population, we found a lower and higher mean premorbid weight in patients with AN and atypical AN, respectively. Considering previous psychological and medical comparisons showing little differences between AN and atypical AN, we view a single disorder as the most parsimonious explanation. Etiological models need to particularly account for the strong relationship between weight loss and premorbid body weight.

An examination of adults with atypical anorexia nervosa at admission to treatment at higher levels of care: An attempt to increase diagnostic clarity

OBJECTIVE

Anorexia nervosa (AN) is a serious illness with a high mortality rate and multiple physiological complications. The vague definition of atypical AN allows for subjective interpretation. This retrospective study aimed to focus future research on the operational definition of atypical AN by examining four factors associated with atypical AN at admission to higher level of care treatment.

METHODS

Adults with atypical AN (n = 69) were examined within sample analyses among four groups: (1) >10% versus ≤10% weight loss; (2) weight loss within the previous 3 months versus >3 months; (3) engaging in purging behaviors versus absence of purging behaviors; and (4) endorsing versus not endorsing significant cognitive aspects of AN.

RESULTS

Patients with atypical AN endorsed elevated ED cognitions on the Eating Disorder Examination-Questionnaire and depressive symptoms; a lack of association was found between weight loss severity and weight loss time frame with depressive symptoms, eating concern, and restraint. Purging behavior was associated with a higher expected body weight percentage (%EBW) and dietary restraint, while greater AN cognitions were associated with a higher EBW and weight loss percentage. Few patients demonstrated bradycardia, hypophosphatemia, or amenorrhea.

DISCUSSION

This study demonstrated the severity of ED cognitions and depressive symptoms in this atypical AN sample and provided directions for future studies in the nosology of atypical AN. It may be important to distinguish between individuals with atypical AN who are purging and those who are not. Atypical AN was associated with a low frequency of physiological disturbances.

PUBLIC SIGNIFICANCE

This study provides further clarification regarding the operational definition of atypical AN; currently, a constellation of symptoms under Other Specified Feeding or Eating Disorders. This study was consistent with previous research in reporting severe eating disorder cognitions in adults with atypical AN, and noted the potential importance of distinguishing a purging distinction. A minority of patients in this study had physiological impairments.

Differentiation between atypical anorexia nervosa and anorexia nervosa using machine learning

OBJECTIVE

Body mass index (BMI) is the primary criterion differentiating anorexia nervosa (AN) and atypical anorexia nervosa despite prior literature indicating few differences between disorders. Machine learning (ML) classification provides us an efficient means of accurately distinguishing between two meaningful classes given any number of features. The aim of the present study was to determine if ML algorithms can accurately distinguish AN and atypical AN given an ensemble of features excluding BMI, and if not, if the inclusion of BMI enables ML to accurately classify between the two.

METHODS

Using an aggregate sample from seven studies consisting of individuals with AN and atypical AN who completed baseline questionnaires (N = 448), we used logistic regression, decision tree, and random forest ML classification models each trained on two datasets, one containing demographic, eating disorder, and comorbid features without BMI, and one retaining all features and BMI.

RESULTS

Model performance for all algorithms trained with BMI as a feature was deemed acceptable (mean accuracy = 74.98%, mean area under the receiving operating characteristics curve [AUC] = 74.75%), whereas model performance diminished without BMI (mean accuracy = 59.37%, mean AUC = 59.98%).

DISCUSSION

Model performance was acceptable, but not strong, if BMI was included as a feature; no other features meaningfully improved classification. When BMI was excluded, ML algorithms performed poorly at classifying cases of AN and atypical AN when considering other demographic and clinical characteristics. Results suggest a reconceptualization of atypical AN should be considered.

PUBLIC SIGNIFICANCE

There is a growing debate about the differences between anorexia nervosa and atypical anorexia nervosa as their diagnostic differentiation relies on BMI despite being similar otherwise. We aimed to see if machine learning could distinguish between the two disorders and found accurate classification only if BMI was used as a feature. This finding calls into question the need to differentiate between the two disorders.

Eating Disorders in Youth with Chronic Health Conditions: Clinical Strategies for Early Recognition and Prevention

Youth with chronic health conditions face an elevated risk of eating disorders and disordered eating behaviors. Contributors to this phenomenon may include the unique threats faced by this vulnerable population to their body image, their relationships with food and eating, and their mental health and self-esteem. However, youth with chronic health conditions may also experience more severe medical complications and mortality from eating disorder behaviors because of the additional risks conveyed by their underlying conditions. In this review, clinical strategies are provided to support youth with chronic health conditions through early recognition of eating disorder behaviors and prompt referral to treatment, which is important for a better prognosis. Suggestions are also given to mitigate their risk of developing eating disorders by proactively addressing risk factors and offering thoughtful anticipatory guidance that promotes a positive relationship with food and eating.

Identification of State Markers in Anorexia Nervosa: Replication and Extension of Inflammation Associated Biomarkers Using Multiplex Profiling in Anorexia Nervosa and Atypical Anorexia Nervosa

Proteomics provides an opportunity for detection and monitoring of anorexia nervosa (AN) and its related variant, atypical-AN (atyp-AN). However, research to date has been limited by the small number of proteins explored, exclusive focus on adults with AN, and lack of replication across studies. This study performed Olink Proseek Multiplex profiling of 92 proteins involved in inflammation among females with AN and atyp-AN (N = 64), all < 90% of expected body weight, and age-matched healthy controls (HC; N=44). After correction for multiple testing, nine proteins differed significantly in the AN/atyp-AN group relative to HC group ( lower levels: CXCL1, HGF, IL-18R1, TNFSF14, TRANCE; higher levels: CCL23, Flt3L, LIF-R, MMP-1). The expression levels of three proteins ( lower IL-18R1, TRANCE; higher LIF-R) were uniquely disrupted in females with AN. No unique expression levels emerged for atyp-AN. Across the whole sample, twenty-one proteins correlated positively with BMI (ADA, AXIN1, CD5, CD244, CD40, CD6, CXCL1, FGF-21, HGF, IL-10RB, IL-12B, IL18, IL-18R1, IL6, LAP TGF-beta-1, SIRT2, STAMBP, TNFRSF9, TNFSF14, TRAIL, TRANCE) and six (CCL11, CCL23, FGF-19, IL8, LIF-R, OPG) were negatively correlated with BMI. Overall, our results replicate the prior study demonstrating a dysregulated inflammatory status in AN, and extend these results to atyp-AN (AN/atyp-AN all < 90% of expected body weight). Of the 27 proteins correlated with BMI, 18 were replicated from a prior study using similar methods, highlighting the promise of inflammatory protein expression levels as biomarkers of disease monitoring. Additional studies of individuals across the entire weight spectrum are needed to understand the role of inflammation in atyp-AN.